Monday, October 3, 2016

Primary and surveys : train station not to play through – Release

a year ago, Libe offered you a calculator to verify the reliability of the polls for regional elections. With the multiplication of the primary right, the socialist Party and in the green season of the surveys returned. And with them, the headlines without precautions.

Read our decryptionPrimary to the right : how do you read the polls

Since April, the records of the surveys published are available online on the website of the Commission surveys. They often say a little more than the articles that are showing. To read these surveys, it is necessary to pay attention to two items in particular.

The first is the size of the sub-sample. Indeed, to have a score to submit, the pollsters do not keep in their survey that the responses of people “certain to participate in the primary”. With a participation rate of 9% of the respondents to the primary of the right, or 4% for the primary of the left, the sub-samples are very small. And the margin of error is the shot even greater.

The second, it is the part of the undecided. Even if respondents are “certain to vote”, they do not yet know for whom. But their number is often tucked away into a corner to have a nice score between candidates whose total is 100%. Replace the scores in the calculator below to get a sense of the results of the polls.

Take for example, the BVA survey published on Monday 3 October. the “A poll gives Holland beaten by Montebourg”, Le Figaro, for example. The scores given for the two men are, respectively, 52% for the former minister and 48% for the president. First of all, cut out a detail : the assumptions are only assumptions. Neither François Hollande or Manuel Valls, however, tested are candidates. Arnaud Montebourg, at the time the survey was done was not officially.

leaning on the manual, we see that the sample is of 9 255 people, but only the sub-sample of respondents “certain to vote in the primary” is about 370 people (this figure is not given, so it is more or less 4% 9 925). We can also read that 24% of those polled have yet to notice for the first round, and 22% do not have it on the second. Taking into account all these elements, the score of François Hollande is between 32% and 41% and that of Arnaud Montebourg between 35% and 44%. Thus far of the relentless victory of the former minister.